Semiconductor light-emitting device and process for production thereof

ABSTRACT

One aspect of the present invention provides a semiconductor light-emitting device improved in luminance, and also provides a process for production thereof. The process comprises a procedure of forming a relief structure on the light-extraction surface of the device by use of a self-assembled film. In that procedure, the light-extraction surface is partly covered with a protective film so as to protect an area for an electrode to be formed therein. The electrode is then finally formed there after the procedure. The process thus reduces the area incapable, due to thickness of the electrode, of being provided with the relief structure. Between the electrode and the light-extraction surface, a contact layer is formed so as to establish ohmic contact between them.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority fromthe prior International Application No. JP2009/65756 filed on Sep. 9,2009; the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a process for production of asemiconductor light-emitting device in which an improved reliefstructure is formed on the light-extraction surface, and also relates tothe semiconductor light-emitting device produced thereby.

2. Description of Related Art

For the purpose of improving the light-extraction efficiency of asemiconductor light-emitting device such as a light-emitting diode(LED), it has hitherto been proposed to form a relief structure on thelight-extraction surface of the device by use of a self-assembled blockcopolymer film as a mask (see, Patent documents 1, 2).

The relief structure is generally formed after an electrode is providedon the light-extraction surface. Specifically, first a self-assembledfilm is formed by spin-coating on the light-extraction surfacepreviously provided with an electrode thereon, and then thelight-extraction surface is dry-etched through the pattern ofself-assembling as a mask to form a relief structure. However, since theelectrode normally has a thickness of 1 μm or more, the self-assembledfilm formed thereover by spin-coating has a large step around theelectrode and hence the film in the area covering around the electrodeis locally thicker than the designed thickness. Because of this locallylarge thickness, the self-assembling pattern in the area around theelectrode cannot be transferred onto the light-extraction surface, andconsequently the relief structure is formed in a smaller area. Inparticular, considering that the area around the electrode generallygives off intense luminescence, it is a critical problem that the reliefstructure cannot be formed there. There is thus room for improvement inluminance of the device.

JP-A 2007-220865 (KOKAI) describes a method in which a relief structureis previously formed by photolithography on the light-extraction surfaceand thereafter an electrode is provided thereon. This method enables toform the relief structure in the area near the electrode. However, ifthe light-extraction surface contains semiconductors of high etchingrates such as GaAs, the method cannot form a good relief structure.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a process forproduction of a semiconductor light-emitting device in which a reliefstructure can be formed in an area closer to the electrode on thelight-extraction surface.

One aspect of the present invention resides in a process for productionof a semiconductor light-emitting device having a semiconductor layerthe surface of which a relief structure and an electrode are formed onand light is extracted from; comprising:

stacking an active layer and said semiconductor layer on a substrate,

providing said semiconductor layer with such a contact layer as bringssaid electrode and the surface of said semiconductor layer into ohmiccontact with each other,

forming an oxide film on the surface of said semi-conductor layer in anarea where said electrode is to be formed,

forming a protective film on said semiconductor layer in the wholesurface area including the area where said oxide film is formed,

forming a self-assembled film on said protective film,

fabricating said protective film by dry etching through saidself-assembled film as a mask, to form a protective film mask,

fabricating said semiconductor layer by dry etching through saidprotective film mask, to form said relief structure, and

removing said protective film in the area where said electrode is to beformed, followed by depositing there an electro-conductive material onsaid contact layer to form said electrode.

Another aspect of the present invention resides in a process forproduction of a semiconductor light-emitting device having asemiconductor layer the surface of which a relief structure and anelectrode are formed on and light is extracted from; comprising:

stacking an active layer and said semiconductor layer on a substrate,

forming an oxide film on the surface of said semi-conductor layer in anarea where said electrode is to be formed,

forming a protective film on said semiconductor layer in the wholesurface area including the area where said oxide film is formed,

forming a self-assembled film on said protective film,

fabricating said protective film by dry etching through saidself-assembled film as a mask, to form a protective film mask,

fabricating said semiconductor layer by dry etching through saidprotective film mask, to form said relief structure,

removing said protective film in the area where said electrode is to beformed, followed by depositing an electro-conductive material there onsaid contact layer to form said electrode, and

establishing ohmic contact between said electrode and the surface ofsaid semiconductor layer.

Still another aspect of the present invention resides in a semiconductorlight-emitting device produced by either of the above processes.

Yet another aspect of the present invention resides in a semiconductorlight-emitting device having a semiconductor layer the surface of whicha relief structure and an electrode are formed on and light is extractedfrom, wherein said relief structure is formed in the area of 10 μm orless from the electrode.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view schematically illustrating the structure of aLED produced according to one embodiment of the present invention.

FIG. 2 shows sectional views schematically illustrating a process forproduction of a semiconductor light-emitting device according to oneembodiment of the present invention.

FIG. 3 shows sectional views schematically illustrating a process forproduction of the semiconductor light-emitting device in Example 2.

FIG. 4 shows sectional views schematically illustrating a process forproduction of the semiconductor light-emitting device in Example 3.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the present invention are described below in detail.

FIG. 1 is a sectional view schematically illustrating the structure of aLED produced according to one embodiment of the present invention.

The light-emitting device shown in the drawing comprises a substrate 101of, for example, n-type GaAs. On the substrate 101, a hetero structure102 including, for example, an n-type InAlP clad layer, an InGaP activelayer and a p-type InAlP clad layer is formed and further a currentspreading layer 103 of, for example, p-type InGaAlP is formed thereon.On a part of the current spreading layer 103, a p-side electrode 105 isprovided. Further, a thin GaAs contact layer 104 is provided between theelectrode 105 and the current spreading layer 103 so as to bring theminto ohmic contact with each other. Particularly in the case where thecurrent spreading layer 103 comprises a multi-element material, forexample, a three- or more element material such as InGaAlP or AlGaAs, itis difficult without the contact layer to bring the current spreadinglayer into ohmic contact with the electrode formed thereon. If itresults in failure to establish the ohmic contact, current loss occursto impair the luminance. The contact layer is therefore necessary. Thematerial of the contact layer is normally GaAs, GaP or the like althoughdepending on the semiconductor layer and the electrode, between whichthe contact layer is placed. On the bottom surface of the substrate, ann-side electrode 106 is provided. Luminescence emitted from the activelayer is extracted from the surface of the current spreading layer 103in the area where the electrode 105 is not formed.

In addition, according to one aspect of the present invention,submicro-projections 107 constituting a relief structure are formed onthe bare surface of the current spreading layer in the area where theelectrode is not formed. The relief structure contributes for improvingluminance of the LED. Since a LED generally emits luminescence stronglyfrom an area around the electrode, the relief structure is preferablyformed in an area closer to the electrode. However, according to theconventional process, the relief structure cannot be formed near theelectrode. Specifically, in the conventional process, the electrode andthe submicro-projection of the relief structure are generally so formedthat the interval (A) between them in FIG. 1 is 10 μm or more. This isbecause the electrode is formed before a block copolymer is spin-coatedto form a self-assembled film thereof in the conventional process. Thefilm thus formed over the electrode is locally too thick in the areaaround the electrode, and hence has a step there.

In contrast, the present invention makes it possible to form theelectrode and the submicro-projection of the relief structure so closerthat the interval between them can be made 10 μm or less. Accordingly,the present invention enables to produce a light-emitting device havinga relief structure formed in a larger area. As described above, thepresent invention can remarkably shorten the interval between theelectrode and the submicro-projection of the relief structure. Even so,however, if the interval is less than 1 μm, current density worsespreads in the current spreading layer and consequently light is givenoff from a smaller area of the active layer, to impair the internalluminance efficiency. That is, therefore, not preferred.

[Process for Production of a Light-Emitting Device]

The following describes a process according to one embodiment of thepresent invention for production of a semiconductor light-emittingdevice. The present inventors have already developed a techniqueutilizing a submicro-phase separation structure of block copolymer (see,for example, JP-A 2003-258296 (KOKAI)). That technique can be adopted inthe process of the present invention. The process employing the abovetechnique is explained below in detail by referring to FIG. 2.

First, a hetero structure 102 comprising an n-type InAlP clad layer, anInGaP active layer and a p-type InAlP clad layer is formed on an n-GaAssubstrate 101, and then a current spreading layer 103 of p-type InGaAlPis formed thereon by epitaxial growth. On the current spreading layer, ap-type GaAs contact layer 104 (0.1 μm) is formed for the purpose ofestablishing ohmic contact. On the bottom surface of the substrate, ann-side electrode 106 is formed (FIG. 2 (a)).

Subsequently, a SiO₂ film 201 is formed on the whole surface by chemicalvapor deposition (hereinafter, referred to as “CVD”) (FIG. 2 (b)). Afterthat, a resist film (not shown) is formed on the SiO₂ film 201 and thensubjected to exposure and development to obtain a resist pattern forforming an electrode. By use of the obtained resist pattern, the SiO₂film is fabricated by wet etching. Successively, the GaAs contact layeris also fabricated by wet etching. Finally, the residual resist film isremoved (FIG. 2 (c)). The GaAs contact layer is normally removed in thewhole area other than where the electrode is to be formed.

Thereafter, a protective film, such as a SiO₂ film 202, is provided forthe purpose of forming a relief structure on the substrate. Theprotective film preferably has a thickness of 300 nm or less. If theprotective film has that thickness, a self-assembled film subsequentlyformed thereon can have a reduced local thickness in the area around theelectrode. As a result, the protective film having the above thicknesscan increase the area where the relief structure is formed. The formedSiO₂ film is then spin-coated with a solution of submicro-phaseseparation composition containing block copolymer dissolved in asolvent, to form a block copolymer film 203, which is successivelyprebaked to remove the solvent. The block polymer, for example,comprises a polystyrene segment and a polymethyl methacrylate segment.The block copolymer film is annealed under nitrogen gas atmosphere,whereby the block polymer causes phase separation (FIG. 2 (d)) to formtwo or more polymer fragments (203A, 203B).

Subsequently, the phase-separated block copolymer film shown in FIG. 2(d) is etched by reactive ion etching (hereinafter, referred to as“RIE”). Since the two or more polymer fragments have different etchingrates, some of them are selectively etched to leave a fine polymerpattern 204 shown in FIG. 2 (e).

After that, the SiO₂ film is fabricated by RIE through the polymerpattern 204 as a mask. The gases usable in the RIE are, for example,fluorine-containing gases such as CF₄, CHF₃ and C₄F₈, and they may bedoped with Ar or O₂. After the fabrication by RIE, the polymer mask 204is unnecessary and hence generally removed by oxygen ashing or the like.In this way, a pattern 205 of the protective film (SiO₂) is formed (FIG.2 (f)).

Thereafter, the InGaAlP current spreading layer is fabricated by RIEwith a proper etching gas through the SiO₂ pattern 205 as a mask, toform submicro-projections 107 and consequently to obtain a fine reliefpattern. The gas used in the RIE fabrication is not restricted to Cl₂,and the etching can be performed with BCl₃ or N₃. Further, the gas maybe doped with Ar. After the etching procedure, the SiO₂ film 201 and theSiO₂ pattern 205 are removed to form a relief pattern comprising, forexample, columnar submicro-projections 107 on the surface of the device(FIG. 2 (g)).

Subsequently, the relief pattern is sputtered in an inert gas such as Argas or He gas, and thereby the top and bottom of eachsubmicro-projection 107 are sputtered to obtain a relief structurecomprising submicro-projections in the shapes of cones, columns or mesasshown in FIG. 2 (h).

Finally, the SiO₂ film covering the area for an electrode to be formedtherein is removed by wet etching. After that, a lift-off resist film isformed there and then subjected to exposure and development to providean electrode-forming pattern. Successively, an electrode 206 is formedby, for example, vapor deposition of gold. The resist pattern is thenremoved to form an electrode (FIG. 2 (i)). The process according to thepresent invention can thus give a semiconductor light-emitting device.

The above describes an example in which a SiO₂ film is used as theprotective film for the electrode. However, the protective film is by nomeans restricted to a SiO₂ film, and other films such as SiN, SiON andTiO₂ films are also usable.

The present invention is further explained below in detail by use of thefollowing examples, in which LEDs having relief structures producedaccording to the present invention were compared in luminance withconventional LEDs having relief structures formed after formation of theelectrodes.

In the process according to the present invention, an area for theelectrode to be formed therein is protected in an early stage and thenlater the electrode is formed there, so that a relief structure can beformed in an area closer to the electrode. Consequently, the process ofthe present invention reduces the area where the relief structure is notformed, and makes it possible to form the relief structure in an areaaround the electrode, namely, in an area giving off intenseluminescence. The present invention can thus improve the luminance.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details and representative embodiments shownand described herein. Accordingly, various modifications may be madewithout departing from the spirit or scope of the general inventiveconcept as defined by the appended claims and their equivalents.

EXAMPLES

Example 1

According to the aforementioned process, a LED was produced.

As illustrated in FIG. 2 (a), on an n-GaAs substrate 101, a heterostructure 102 comprising an n-type InAlP clad layer, an InGaP activelayer and a p-type InAlP clad layer was formed. Further, a currentspreading layer 103 containing four elements of p-type InGaAlP wasformed thereon by epitaxial growth. On the current spreading layer 103,a p-type GaAs contact layer 104 (0.1 μm) was formed for the purpose ofestablishing ohmic contact. On the bottom surface of the substrate, ann-side electrode 106 was formed to produce a LED element. The elementgave off luminescence at 635 nm.

Subsequently, a 300-nm thick SiO₂ film 201 was formed on the wholesurface by CVD (FIG. 2 (b)). After that, a 1-μm thick film of i-rayresist (THMR [trademark], manufactured by TOKYO OHKA KOGYO CO., LTD.)was formed on the SiO₂ film and then subjected to exposure anddevelopment to obtain a resist pattern for forming an electrode. By useof the obtained resist pattern, the SiO₂ film was wet-etched withammonium fluoride. Successively, the GaAs contact layer 104 was alsowet-etched with phosphoric acid. Finally, the residual resist wasremoved with a remover (FIG. 2 (c)).

Thereafter, a 100-nm thick SiO₂ protective film 202 was formed by CVDfor the purpose of forming a relief structure on the substrate. Theformed SiO₂ film was then spin-coated at 3000 rpm with a solutioncontaining block copolymer dissolved in a solvent, and successively theapplied solution was prebaked at 110° C. for 90 seconds to remove thesolvent, whereby a 150-nm thick block copolymer film 203 was formed. Theblock polymer comprised a polystyrene (hereinafter, referred to as “PS”)block (molecular weight: 315000) and a polymethyl methacrylate(hereinafter, referred to as “PMMA”) block (molecular weight: 785000).The block copolymer film was then annealed at 210° C. for 4 hours undernitrogen gas atmosphere to separate the phases of PA and PMMA, whereby apattern of approx. 110 nm diameter PS dots was formed (FIG. 2 (d)).

Subsequently, the phase-separated block copolymer film was etched by RIEunder the conditions of O₂ flow: 30 sccm, pressure: 13.3 Pa (100 mTorr),power: 100 W. Since the PS and PMMA had different etching rates, thePMMA was selectively etched to leave a PS pattern 204 shown in FIG. 2(e).

After that, the SiO₂ film 202 was etched through the PS pattern as amask under the conditions of CF₄ flow: 30 sccm, pressure: 1.33 Pa (10mTorr), power: 100 W. After the etching procedure, the remaining PSpattern 204 was unnecessary and hence removed by O₂ ashing. In this way,a SiO₂ mask pattern was formed as shown in FIG. 2 (f).

Thereafter, inductive coupled plasma (hereinafter referred to as “ICP”)etching was carried out for 2 minutes under the conditions ofAr/Cl₂=5/20 sccm, 0.266 Pa (2 mTorr), incident power/bias power=100/300W, to form columnar submicro-projections 107 shown in FIG. 2 (g).

Subsequently, the submicro-projections were sputtered for 60 seconds inAr gas under the conditions of Ar flow: 50 sccm, pressure: 0.65 Ps (5mTorr), power: 300 W. Those conditions were so moderate that thecolumnar submicro-projections 107 were removed not completely but partlyand hence that only the tops and bottoms thereof were sputtered to formsubmicro-projections in the shapes of cones or mesas.

Thereafter, the SiO₂ film 201 covering the area for an electrode to beformed therein was removed by wet etching. After that, a lift-off resist(TLOR [trademark], manufactured by TOKYO OHKA KOGYO CO., LTD.) wascoated thereon to form a 3-μm thick resist film and then subjected toexposure and development to form an electrode-forming pattern.Successively, gold/gold-zinc were vapor-deposited to form a 1-μm thickfilm. The resist was then removed with a remover to form a goldelectrode 206 (FIG. 2 (i)). Finally, annealing treatment was carried outat 400° C. for 30 minutes under nitrogen gas atmosphere so as to bringthe electrode 206 and the GaAs contact layer 104 into ohmic contact witheach other. The above procedures thus gave a semiconductorlight-emitting device (LED) according to the present invention.

Comparative Example 1

Subsequently, a comparative LED comprising a relief structure wasproduced according to the conventional process. Specifically, theprocedures of Example 1 were repeated except that a substrate beforehandprovided with a gold electrode was prepared and a relief structure wasformed thereon.

In the conventionally produced LED of Comparative Example 1, the reliefstructure was formed in the area of at least 12 μm from the electrode.On the other hand, in the LED of Example 1, the relief structure wasformed in the area of at least 1 to 5 μm from the electrode. As a resultof that, the LED of Example 1 was improved by 20% in luminance ascompared with the LED of Comparative Example 1.

Example 2

As illustrated in FIG. 3 (a), on an n-GaP substrate 101, a double heterostructure 102 comprising an n-InAlP clad layer 102B, a p-InAlP cladlayer 102C, and an InGaAlP active layer 102A placed between them wasformed. Further, a p-GaP current spreading layer 103 was formed thereon.This p-GaP current spreading layer served as a contact layer as well asa semiconductor layer from which light was extracted. On the wholebottom surface of the n-GaP substrate, an n-side electrode 106 wasformed to produce a LED element. The element gave off luminescence at612 nm.

Subsequently, a 200-nm thick SiO₂ film 201 was formed on the wholesurface by CVD in the same manner as in Example 1 (FIG. 3 (b)). Afterthat, a 1-μm thick film of i-ray resist (THMR [trademark], manufacturedby TOKYO OHKA KOGYO CO., LTD.) was coated on the SiO₂ film and thensubjected to exposure and development to obtain a resist pattern forforming an electrode. By use of the obtained resist pattern, the SiO₂film was wet-etched with ammonium fluoride. Finally, the residual resistwas removed with a remover (FIG. 3 (c)).

Thereafter, a 70-nm thick SiO₂ protective film 202 was formed by CVD inthe same manner as in Example 1 for the purpose of forming a reliefstructure on the substrate. Successively, a block copolymer film 203 wasprovided and then a phase-separation pattern was formed in the blockcopolymer film in the same manner as in Example 1 (FIG. 3 (d)).

Subsequently, the phase-separated block copolymer film was etched by RIEunder the conditions of O₂ flow: 30 sccm, pressure: 13.3 Pa (100 mTorr),power: 100 W, whereby the phase separated PS and PMMA were etched toleave a PS pattern 204 shown in FIG. 3 (e).

After that, the SiO₂ film 202 was etched through the PS pattern 204 as amask under the conditions of CF₄ flow: 30 sccm, pressure: 1.33 Pa (10mTorr), power: 100 W in the same manner as in Example 1. After theetching procedure, the remaining PS pattern 204 was unnecessary andhence removed by O₂ ashing. In this way, a SiO₂ mask pattern 205 wasformed as shown in FIG. 3 (f).

Thereafter, ICP etching was carried out for 2 minutes under theconditions of BCl₃/Cl₂=5/20 sccm, 0.266 Pa (2 mTorr), incidentpower/bias power=100/100 W, to form columnar submicro-projections 107shown in FIG. 3 (g).

Subsequently, the submicro-projections were sputtered for 60 seconds inAr gas under the conditions of Ar flow: 50 sccm, pressure: 0.65 Ps (5mTorr), power: 300 W in the same manner as in Example 1, whereby thetops and bottoms of the submicro-projections were sputtered to formcone-shaped or mesa-shaped submicro-projections.

Thereafter, the SiO₂ film covering the area for an electrode to beformed therein was removed by wet etching. After that, a lift-off resist(TLOR [trademark], manufactured by TOKYO OHKA KOGYO CO., LTD.) wascoated thereon to form a 3-μm thick resist film and then subjected toexposure and development to form an electrode-forming pattern.Successively, gold/gold-zinc were vapor-deposited to form a 1-μm thickfilm. The resist was then removed with a remover to form a goldelectrode 105 (FIG. 3 (i)). Finally, annealing treatment was carried outat 400° C. for 30 minutes under nitrogen gas atmosphere so as to bringthe electrode 105 and the GaP current spreading layer 103 (also servingas a contact layer) into ohmic contact with each other. The aboveprocedures thus gave a semiconductor light-emitting device (LED)according to the present invention.

Comparative Example 2

Subsequently, a comparative LED comprising a relief structure wasproduced according to the conventional process. Specifically, theprocedures of Example 2 were repeated except that a substrate beforehandprovided with a gold electrode was prepared and a relief structure wasformed thereon.

In the conventionally produced LED of Comparative Example 2, the reliefstructure was formed in the area of at least 10 μm from the electrode.On the other hand, in the LED of Example 2, the relief structure wasformed in the area of at least 1 to 3 μm from the electrode. As a resultof that, the LED of Example 2 was improved by 25% in luminance ascompared with the LED of Comparative Example 2.

Example 3

As illustrated in FIG. 4 (a), on an n-type GaN substrate 101, anInGaN/GaN MQW active layer 401 comprising an n-type GaN buffer layer andan n-type GaN clad layer, a p-type AlGaN cap layer 402, and a p-type GaNcontact layer 103 were formed by epitaxial growth. On the bottom surfaceof the substrate, an n-side electrode 106 was formed to produce alight-emitting element. The n-side electrode was made of Ti. Theproduced light-emitting diode (LED) gave off luminescence at 400 nm.

Subsequently, a 300-nm thick SiO₂ film 201 was formed on the wholesurface by CVD in the same manner as in Example 1 (FIG. 4 (b)). Afterthat, a 1-μm thick film of i-ray resist (THMR [trademark], manufacturedby TOKYO OHKA KOGYO CO., LTD.) was coated on the SiO₂ film 201 and thensubjected to exposure and development to obtain a resist pattern forforming an electrode. By use of the obtained resist pattern, the SiO₂film 201 was wet-etched with ammonium fluoride. Finally, the residualresist was removed with a remover (FIG. 4 (c)).

Thereafter, a 130-nm thick SiO₂ protective film 202 was formed by CVD inthe same manner as in Example 1 for the purpose of forming a reliefstructure on the substrate. Successively, a block copolymer film 203 wasprovided and then a phase separation pattern was formed in the blockcopolymer film in the same manner as in Example 1 (FIG. 4 (d)).

Subsequently, the phase-separated block copolymer film was etched by RIEunder the conditions of O₂ flow: 30 sccm, pressure: 13.3 Pa (100 mTorr),power: 100 W, and thereby the phase separated PS and PMMA were etched toleave a PS pattern 204 shown in FIG. 4 (e).

After that, the SiO₂ film 202 was etched through the PS pattern 204 as amask under the conditions of CF₄ flow: 30 sccm, pressure: 1.33 Pa (10mTorr), power: 100 W in the same manner as in Example 1. After theetching procedure, the remaining PS pattern 204 was unnecessary andhence removed by O₂ ashing. In this way, a SiO₂ mask pattern 205 wasformed as shown in FIG. 4 (f).

Thereafter, ICP etching was carried out for 150 seconds under theconditions of BCl₃/Cl₂=5/20 sccm, 0.266 Pa (2 mTorr), incidentpower/bias power=100/300 W, to form columnar submicro-projections 107shown in FIG. 4 (g).

Subsequently, the submicro-projections were sputtered for 60 seconds inAr gas under the conditions of Ar flow: 50 sccm, pressure: 0.65 Ps (5mTorr), power: 300 W in the same manner as in Example 1, whereby thetops and bottoms of the submicro-projections were sputtered to formcone-shaped or mesa-shaped submicro-projections.

Thereafter, the SiO₂ film covering the area for an electrode to beformed therein was removed by wet etching. After that, a lift-off resist(TLOR [trademark], manufactured by TOKYO OHKA KOGYO CO., LTD.) wascoated thereon to form a 3-μm thick resist film and then subjected toexposure and development to form an electrode-forming pattern.Successively, nickel and gold were vapor-deposited to form a 1-μm thickfilm. The resist was then removed with a remover to form a nickel-goldelectrode (FIG. 4 (i)). The above procedures thus gave a semiconductorlight-emitting device (LED) according to the present invention.

Comparative Example 3

Subsequently, a comparative LED comprising a relief structure wasproduced according to the conventional process. Specifically, theprocedures of Example 3 were repeated except that a substrate beforehandprovided with a nickel-gold electrode was prepared and a reliefstructure was formed thereon.

In the conventionally produced LED of Comparative Example 3, the reliefstructure was formed in the area of at least 15 μm from the electrode.On the other hand, in the LED of Example 3, the relief structure wasformed in the area of at least 2 to 8 μm from the electrode. As a resultof that, the LED of Example 3 was improved by 20% in luminance ascompared with the LED of Comparative Example 3.

1.-16. (canceled)
 17. A semiconductor light-emitting device having asemiconductor layer the surface of which a relief structure and anelectrode are formed on and light is extracted from, wherein said reliefstructure is formed in the area of 10 μm or less from the electrode. 18.The device according to claim 17, wherein said relief structure isformed in the area of 5 μm or less from the electrode.
 19. The deviceaccording to claim 17, wherein said relief structure is formed in thearea of 3 μm or less from the electrode.
 20. The device according toclaim 17, wherein said relief structure is not formed in the area of 1μm or less from the electrode.
 21. The process according to claim 17,wherein said semiconductor layer is a current spreading layer.
 22. Theprocess according to claim 17, wherein the surface of said semiconductorlayer contains at least three elements.
 23. The process according toclaim 17, wherein the surface of said semiconductor layer contains atleast one material selected from the group consisting of InGaAlP, AlGaAsand AlGaN.
 24. The process according to claim 17, wherein said contactlayer contains GaAs or GaN.
 25. The process according to claim 17,wherein said electroconductive material is gold, gold-zinc alloy,gold-germanium alloy or gold-nickel alloy.